Obesity can lead to a number of life-threatening and morbidity-producing disease states such as diabetes mellitus, heart disease, vascular disease, osteoarthritis, gout, and obstructive sleep apnea. Body mass index [kg body mass/(meters height)2] is used as a measure of obesity; a patient with a BMI of 25.0-29.9 kg/m2 is considered overweight, while a BMI greater than 30.0 kg/m2 considered obese. If diet and exercise are unsuccessful in achieving or maintaining an optimal or ideal body weight, and if the patient has a BMI greater than 40 kg/m2 (or a BMI greater than 35 kg/m2 with coexisting morbid conditions), a bariatric surgical procedure may be performed to induce weight loss. Bariatric surgeries are generally categorized as having a restrictive effect, a malabsorptive effect, or both effects. A restrictive effect refers to creating a surgical constriction at the area where food exits the esophagus or proximal stomach and/or reducing the size of the stomach, which acts a food reservoir. By restricting exit of food from the esophagus and proximal stomach and by restricting the size and/or compliance of the stomach, the stomach (or its remnant) fills with a small amount of food and the patient experiences early fullness or satiety. Such an effect either makes it uncomfortable to eat additional food or diminishes appetite (induces satiety). A malabsorptive effect refers to changing the digestive tract anatomy so that absorption of nutrients from food intake is limited or altered in some manner and/or the intake of excessive amount of food causes the patient to have adverse symptoms. In addition to these effects of bariatric surgery that are related to surgically altered digestive tract anatomy, other effects on endocrine and neural systems that include the gastrointestinal tract have also been recently appreciated as having significant anti-obesity or anti-diabetic effects (see U.S. patent application Ser. No. 12/114628 of Kelly et al., filed May 2, 2008).
The most common bariatric surgical procedure performed is the Roux-en-Y gastric bypass (RGB), which is considered both a restrictive and malabsorptive procedure. Other techniques, performed less commonly, include sleeve gastrectomy and biliopancreatic diversion (BPD). Each operative technique has a physiological effect that is related to the post-surgical reconstructed anatomy. An anatomical structure common to the RGB and BPD is a small pouch at the end of the esophagus, formed from a portion of the proximal stomach and then connected in a new manner to a portion of the small intestine via a structure known as a stoma (typically a gastrojejunostomy stoma). Similarly, the sleeve gastrectomy permanently removes a large portion of the body of the stomach, creating a narrow tubular stomach that empties into the small intestine. The pouch and stoma of the RGB and BPD, as well as the tube of the sleeve gastrectomy, all restrict the flow of food passage from the esophagus to the rest of the digestive tract, thus causing a sensation of early fullness or satiety. Further, while the stomach can hold large amounts of food, the capacity of the surgically-formed gastric pouch or sleeve is quite limited, and thus the patient cannot take in large quantities of food and liquids due to a low reservoir capacity. Malabsorption is also an important effect of bariatric surgical procedures, which contributes to cause weight loss, in addition to the restrictive effects of these procedures.
The reported effectiveness of RGB and other such operations is quite high, with patients losing an average of 60-70% of their excess body weight within about one year. Excess body weight is the amount of body mass above the ideal body weight for a patient, while excess body weight loss is the percentage of the excess body weight that is lost as a result of the surgical intervention for a patient. A successful bariatric surgical procedure is considered one in which the patient achieves>50% excess body weight loss. Some patients fail to ever achieve a 50% excess body weight loss at any time after surgery, although this represents the minority of patients. Within the initial surgical successes, approximately 25% of patients regain all or a significant portion of the previously lost weight and are then considered surgical failures. The reasons for weight regain may include dilation of the pouch and/or stoma in the case of the RGB and BPD, while in gastric sleeve resection patients the newly tubularized stomach may dilate. In all three scenarios, more food is able to be stored in the pouch and tubularized stomach due to dilation, therefore early satiety is not achieved, and the food may pass more quickly into the small intestine, therefore making more room for more food to be eaten. Dilation can be observed in endoscopic examination where the structure appears visibly larger in one or more dimensions, specifically inner diameter, than the ideal size achieved at prior surgery. Dilation can result from an increase in compliance or distensibility of the structure, which is not detectable on endoscopic examination. Increased compliance of the pouch/tube will allow the structure to stretch to accommodate more food and liquid, while increased compliance of the stoma will allow food and liquid to pass more readily. In both cases, there is a loss of the sensation of early satiety which allows the person to take in larger quantities of food and liquid at more frequent intervals, thus resulting in regain of weight.
For patients that have undergone a bariatric surgical procedure and have regained some or all of their excess body weight, the options for additional therapy to re-achieve weight loss are very limited. A repeat surgical procedure to revise the altered gastrointestinal anatomy carries a very high risk for surgical morbidity and mortality. Such revision surgical procedures might alter the pouch and stoma, or might alter the gastric tube, but with uncertain results. These types of revisional procedures are not commonly performed due to patient risk. Others have attempted a non-surgical, endoscopic revision procedure with the placement of endoscopic suture material and other such mechanical structures to reduce the size of the pouch/stoma and gastric tube, although these are temporary interventions. When the suture or structure falls out or is absorbed by the body, the previously dilated anatomy may recur and weight gain return. Therefore, a viable, non-surgical, endoscopic device and method which would result in a permanent alteration of the stoma/pouch and gastric sleeve which would reduce the size and/or compliance of the structure(s), would be desirable.